Downhole Electrical System

ABSTRACT

A cooling device for a drilling tool to be used in a wellbore, comprising an inner sleeve that forms a central void, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler, comprising a hot-side and a cold side, positioned in the annular space, wherein the central void is at least partially filled with instrumentation, and the at least one thermoelectric cooler prevents the instrumentation from attaining a predetermined temperature set-point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 62/134,267 filed Mar. 17, 2015, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a temperature control device for a drilling tool, wherein the temperature control device protects temperature sensitive electronics from exposure to extreme temperatures experienced in the borehole during drilling, for example directional down-hole drilling.

BACKGROUND OF INVENTION

Directional drilling is the practice of drilling vertical and non-vertical wells for the recovery of gas and oil from buried deposits. Directional drilling technology comprises a drill string, which is typically made up of three sections: a bottom hole assembly (BHA), heavy weight drill pipe (HWDP), and drill pipe.

The BHA is typically made up of: a drill bit, which is used to break up the rock formations; drill collars, which are heavy, thick-walled tubes used to apply weight to the drill bit; and drilling stabilizers, which keep the assembly centered in the hole. Other components included in the BHA are items such as a downhole motor, a rotary steerable system, and “Measurement While Drilling” (MWD) components. The BHA components are joined together using rugged threaded connections. Short “subs” are used to connect items with dissimilar threads. The HWDP may be used to make the transition between the drill collars and drill pipe. The function of the HWDP is to provide a flexible transition between the drill collars and the drill pipe. This helps to reduce the number of fatigue failures seen directly above the BHA. A secondary use of HWDP is to add additional weight to the drill bit.

Drill pipe makes up the majority of the drill string back up to the surface. Each drill pipe comprises a long tubular section with a specified outside diameter (e.g. 3½ inch (8.9 cm), 4 inch (10.2 cm), 5 inch (12.7 cm), 5½ inch (13.97 cm), 5⅞ inch (14.9 cm), 6⅝ inch (16.8 cm), among others). Located at each end of a section of the drill pipe are tubular larger-diameter portions called the tool joints. One end of the drill pipe has a male (“pin”) connection, while the other has a female (“box”) connection. The tool joint connections are threaded which allows for the connection of each drill pipe segment to the next segment.

Most components in a drill string are manufactured in 31 foot lengths although they can also be manufactured in 46 foot lengths. Each 31-foot component is referred to as a joint. Typically, 2, 3 or 4 joints are joined together to make a stand.

Drilling fluid is a key component to directional drilling and operation of the drill string. The main functions of drilling fluids include providing hydrostatic pressure to prevent formation fluids from entering into the well bore, transport of drill cuttings out of the hole, and to provide power to a mud motor. Mud motors are typically progressive cavity positive displacement pumps and are also referred to as drilling motors.

Down hole drilling for oil and gas exploration and extraction applications leverages many different types of electronic instruments. These systems are used for real time data logging of rock formations and position, and allow data acquisition in extremely harsh environments. Operating life is critical due to the reliability needs of these tools and the costs associated with pulling and replacing instrumentation that has failed due to high temperature. Tool replacement costs need to be minimized for a well to be economical.

One type of electronic measurement system used in down hole drilling methods is a “Measurement While Drilling” (MWD) system. MWD systems take measurements from sensors located right above the drill bit on the drill string itself. MWD systems are generally capable of taking directional surveys in real time. The MWD system uses sensors (such as accelerometers and magnetometers) to measure the inclination and azimuth of the wellbore at the location of the MWD system. The MWD system also transmits information from the sensors to the surface. With a series of surveys, measurements of inclination, azimuth, and tool face, at appropriate intervals (typically anywhere from every 30 ft to every 500 ft), the location of the wellbore can be calculated. For an operator of a directional driller to steer the well towards a target zone, the operator must know where the well is going, and the effects of the operator's steering efforts. The MWD electronics provide the data needed to accomplish these goals.

It is recognized in the field of directional drilling utilizing MWD systems, that the electronic components present in the drill string must be protected from the excessive temperatures experienced in the well. Many electronics experience unacceptable failure rates at temperatures above 175° C. (347° F.). With well temperatures exceeding 200° C. (392° F.), there is a need for innovative, modular and cost-effective means for cooling and maintaining operation temperatures of drilling MWD systems.

Thermoelectric coolers (TEC) are small, solid-state electronic devices that are being utilized in a variety of technologies that require compact reliable cooling, including electronic enclosures, laser diodes, laboratory instruments, telecommunication devices and missile and space systems. Heat transport utilizing TECs can vary from milliwatts to several thousand watts. TECs operate on the principal of the Peltier Effect. When a voltage or DC current is applied to two dissimilar conductors, a circuit can be created that allows for continuous heat transport between the conductor junctions. One junction is attached to a heat source and the other junction is attached to a heat sink that transfers the heat away. The side facing the heat source is considered the cold side, and the side facing the heat sink, the hot side. There are some examples in the literature in which TECs are used to cool drilling equipment (each of the following patents is incorporated herein by reference in its entirety).

U.S. Pat. No. 5,730,217 describes a system for extending the life span of electronic components in a high temperature well utilizing TECs in combination with a vacuum insulating means. However, vacuum systems can be difficult to maintain, as even very small leaks will result in the loss of vacuum.

U.S. Pat. No. 7,308,795 describes a node for linking successive drill pipe joints, the node comprising electronics cooled by thermoelectric cooling devices.

U.S. Pat. No. 7,527,101 describes a system that actively collects and consumes the waste heat generated in a downhole drilling device, wherein TECs are in conductive contact with the waste heat generating devices.

U.S. Pat. No. 7,571,770 describes the use of thermoionic coolers for downhole drilling applications.

U.S. Pat. No. 7,647,979 describes the use of thermoelectric coolers and thermoelectric generators for downhole applications.

U.S. Pat. No. 5,931,000 describes a cooling system comprising TECs mounted in the drill pipe portion of a downhole assembly that transfers heat from an electronic component mounted in the drill pipe, through the pipe wall, where the heat is ejected to the drilling fluid.

There is still a need in the directional drilling industry for a universal, modular and cost-effective system for cooling MWD systems, as well as the other electronic components of a drill string. The present invention provides an innovative system that utilizes thermoelectric coolers to fulfill this long-felt need.

SUMMARY OF INVENTION

An aspect of the present invention is a cooling device for a drilling tool to be used in a wellbore, comprising an inner sleeve that forms a central void, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler, comprising a hot-side and a cold side, positioned in the annular space, wherein the central void is at least partially filled with instrumentation, and the at least one thermoelectric cooler prevents the instrumentation from attaining a predetermined temperature set-point. The cooling device may further comprise an insulating material in the first annular space.

Another aspect of the present invention is a drilling tool, comprising an embodiment of the cooling device described above and a collar, wherein the cooling device is centrally located inside the collar, with the collar and the cooling device aligned along the same axis, whereby the collar and cooling device form a second annular space through which a drilling fluid passes by the drilling tool, wherein the at least one thermoelectric cooler transfers heat to the drilling fluid, and wherein the collar forms a third annular space between the collar and the wellbore, through which the drilling fluid exits the wellbore.

Another aspect of the present invention is a cooling device for an instrumentation system to be used in a wellbore, comprising an inner sleeve that forms a central void that houses the instrumentation system, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler positioned in the annular space, whereby the at least one thermoelectric cooler prevents the instrumentation from attaining a predetermined temperature set-point.

Another aspect of the present invention is a modular cooling device for a cylindrical drilling instrumentation system, comprising an inner sleeve, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler positioned in the annular space, wherein the inner sleeve fits around and is in direct contact with the drilling instrumentation system.

This Summary is neither intended nor should it be construed as being representative of the full extent and scope of the present disclosure. Moreover, references made herein to “the present invention” or aspects thereof, should be understood to mean certain embodiments of the present disclosure and should not necessarily be construed as limiting all embodiments to a particular description. The present disclosure is set forth in various levels of detail in this Summary as well as in the attached drawings and the Description of Embodiments and no limitation as to the scope of the present disclosure is intended by either the inclusion or non-inclusion of elements, components, etc. in this Summary. Additional aspects of the present disclosure will become more readily apparent from the Description of Embodiments, particularly when taken together with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates some aspects of a prior art drill string;

FIG. 2 illustrates an embodiment of the inner sleeve of the present invention with an array of thermal electric coolers;

FIG. 3 illustrates a perspective view of an embodiment of the inner sleeve, the outer sleeve, and an insulating material and thermoelectric coolers in the annular space between;

FIG. 4 illustrates an embodiment of the outer sleeve and a power source, including the bull nose; and

FIG. 5 illustrates a cross-sectional view of a cooling device of this disclosure stabilized inside the collar of a drilling tool.

DESCRIPTION OF EMBODIMENTS

This disclosure provides a cooling device for a drilling tool to be used in a wellbore, comprising an inner sleeve that forms a central void, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler, comprising a hot-side and a cold side, positioned in the annular space, wherein the central void is at least partially filled with instrumentation, and the at least one thermoelectric cooler prevents the instrumentation from attaining a predetermined temperature set-point.

FIG. 1 illustrates a conventional drilling rig (10) formed over a borehole in which drill string (12) is located. Drill string (12) includes drill pipes (13), bottom hole assembly (BHA, 14), and bit (15). Temperature control devices of this disclosure may be located within the components of a conventional drill string.

The drilling tool may be a bottom hole assembly, a transition pipe, a drill pipe, a joint, a sub, a connection, a heavy wall drill pipe, any other drill string component, and/or any instrumentation associated with any of these drill string components.

The instrumentation may include measurement while drilling instrumentation, and/or electronic components. The instrumentation may include logging while drilling instrumentation, and/or electronic components.

The instrumentation may include accelerometers and magnetometers to measure the inclination and azimuth of the wellbore, wellbore drift, toolface orientation, temperature, pressure, resistivity, conductance, magnetic survey tools, steering tools, gyroscopic survey tools, and any other instrumentation relevant to drilling.

FIG. 2 illustrates an inner sleeve (20) of this disclosure with an array of thermal electric coolers (24) and connective wiring (22). The inner sleeve may be characterized by an inside diameter (26) that may vary from a nominal size of about one inch (2.54 cm) to about 5.5 inches (13.97 cm), depending on the application. The inner sleeve may be more specifically characterized by an inside diameter of about 1.875 inches (4.76 cm).

The inner sleeve may be characterized by a wall thickness ranging from about 0.031 inches (0.08 cm) to about 0.75 inches (1.9 cm), depending on the application. The inner sleeve may be more specifically characterized by a wall thickness of about 0.031 inches (0.08 cm).

The inner sleeve may be constructed from a metal, a plastic, a polymer, a ceramic, or combinations thereof.

The inner sleeve may be constructed from at least one metal or metal alloy comprising copper beryllium and some other non-ferrous metal. Examples of non-ferrous metals include, but are not limited to, aluminum, nickel, tin, titanium and zinc. Non-ferrous alloys typically include brass.

FIG. 3 illustrates a perspective view of an inner sleeve (32), located within an outer sleeve (30), forming an annular space (34) between the inner sleeve (32) and the outer sleeve (30). The annular space (34) contains an insulating material and thermoelectric coolers (36).

The outer sleeve may be characterized by an inside diameter ranging from about 0.125 inches (0.32 cm) to about one inch (2.54 cm) larger than the outside diameter of the inner sleeve, depending on the application. The outer sleeve may be more specifically characterized by an inside diameter about 0.25 inches (0.64 cm) larger than the outside diameter of the inner sleeve.

The outer sleeve may be characterized by a wall thickness ranging from about 0.031 inches (0.08 cm) to about 0.75 inches (1.9 cm), depending on the application. The outer sleeve may be more specifically characterized by a wall thickness of about 0.031 inches (0.08 cm).

The outer sleeve may be constructed from a metal, a plastic, a polymer, a ceramic, or combinations thereof. For example, the outer sleeve may be constructed from at least one metal or metal alloy comprising copper beryllium, and some other non-ferrous metal.

The at least one thermoelectric cooling device may comprise a p-type semiconductor and/or an n-type semiconductor. At least two thermoelectric devices may be connected in parallel or connected in series. The thermoelectric cooling device, or devices, may be doped with a metal dopant, such as a dopant selected from a Group IV or Group V metal. The thermoelectric cooling device, or devices, may be constructed from materials selected from Bi₂Te₃, Sb₂Te₃, lead telluride and its alloys, SiGe, and combinations thereof. The at least one thermoelectric cooler may be a linear or multistage thermoelectric cooler.

The at least one thermoelectric cooler can enable the instrumentation to maintain an instrumentation operational temperature that has a differential temperature from about 60° C. to about 150° C. less than the wellbore environmental temperature. The at least one thermoelectric cooler can maintain a differential temperature between the hot-side and cold-side of at least about 60° C. to about 150° C.

FIG. 4 illustrates an embodiment of the outer sleeve (40), including a power source (42), and bull nose (44) at the lower end of the assembly.

The at least one thermoelectric cooler may be battery operated. The battery may be a lithium ion battery. A range of batteries may be provided per temperature control device. Alternatively or additionally, the at least one thermoelectric cooler may be powered by an external power supply from the surface. Alternatively or additionally, the at least one thermoelectric cooler may share a power supply with the power supply used for the instrumentation.

The polarity of the power supplying the at least one TEC device may be switched such that the device heats instead of cools. Thus, a temperature control loop and a switch may be supplied with the at least one TEC device, such that when the temperature control loop reaches a predetermined set-point, the power supply polarity is changed via the switch, thus changing the TEC from a cooling mode to a heating mode, or vice versa.

The hot-side of the at least one thermoelectric cooler may be in direct contact with the outer sleeve. Similarly, the cold-side of the thermoelectric cooler may be in direct contact with the inner sleeve.

FIG. 5 illustrates a cross-sectional view of a cooling device of this disclosure stabilized inside the collar of a drilling tool and located in a borehole. In this figure, electronics, such as directional drilling electronic control components, may be located in the interior (62) of the inner sleeve (60). TEC (58) are positioned on the exterior surface of the inner sleeve (60), in contact with an insulating material located between the inner sleeve (60) and outer sleeve (54). The cooling device (64) thus includes the inner sleeve (60) with TEC (58) on the exterior surface and an outer sleeve (54) with an insulating material located between the inner sleeve (60) and outer sleeve (54) in contact with the TEC (58). The borehole (66) in the rock (50) encloses drill fluid (52) between the bore hole (66) and collar (72), which is stabilized by axial support (70). Drill fluid located in the annular space (68) between outer sleeve (54) and collar (72).

Thus, the cooling device may include an insulating material in the first annular space. The insulating material may comprise a polymer, a glass, a ceramic, a gas, a vacuum, and combinations thereof. The insulating material may be an expandable epoxy, such as Hysol MA557. Alternatively or additionally, the insulating material may comprise a gas. Such insulating gas may be present at about atmospheric pressure (e.g. approximately 14.7 psia). Alternatively, the insulating gas may be present at less than atmospheric pressure.

When insulating material is present, the cold-side of the at least one thermoelectric cooler may be in direct contact with the inner sleeve, and the hot-side of the at least one thermoelectric cooler may be in direct contact with the insulating material.

The cooling device may further comprise thermally conductive bridges, wherein the cold-side of the at least one thermoelectric cooler is in direct contact with the inner sleeve, and the hot-side of the at least one thermoelectric cooler is in direct contact with one end of a thermally conductive bridge, and the opposing end of the thermally conductive bridge is in direct contact with the outer sleeve.

Another aspect of the present invention is a cooling device for an instrumentation system to be used in a wellbore, comprising an inner sleeve that forms a central void that houses the instrumentation system, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler positioned in the annular space, whereby the at least one thermoelectric cooler prevents the instrumentation from attaining a predetermined temperature set-point.

Another aspect of the present invention is a modular cooling device for a cylindrical drilling instrumentation system, comprising an inner sleeve, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler positioned in the annular space, wherein the inner sleeve fits around and is in direct contact with the drilling instrumentation system.

In another aspect, the present invention provides a method for cooling a downhole drill string and specifically, electrical components located in the drill string. These methods include locating a downhole drill string in a drill hole, the drill string including an inner sleeve, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler (TEC) positioned in the annular space. The electrical components are located in and are in direct contact with the inner sleeve. The at least one TEC is supplied with energy to cool the electrical components located in the inner sleeve during a drilling process, such as a directional drilling process. In these methods, the annular space between the inner sleeve and the outer sleeve may contain an insulating material.

The foregoing description of the present disclosure has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the disclosure to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present disclosure. The embodiments described hereinabove are further intended to explain the best mode known for practicing the disclosure and to enable others skilled in the art to utilize the disclosure in such, or other, embodiments and with various modifications required by the particular applications or uses of the present disclosure. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art. 

What is claimed is:
 1. A cooling device for a drilling tool to be used in a wellbore, comprising: an inner sleeve that forms a central void; an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating an annular space between the inner sleeve and the outer sleeve; and at least one thermoelectric cooler, comprising a hot-side and a cold side, positioned in the annular space, wherein the central void is at least partially filled with instrumentation, and the at least one thermoelectric cooler prevents the instrumentation from attaining a predetermined temperature set-point.
 2. The cooling device of claim 1, wherein the hot-side is in direct contact with the outer sleeve and the cold-side is in direct contact with the inner sleeve.
 3. The cooling device of claim 1, further comprising an insulating material in the first annular space.
 4. The cooling device of claim 3, wherein the cold-side is in direct contact with the inner sleeve.
 5. A cooling device for an instrumentation system to be used in a wellbore, comprising: an inner sleeve that forms a central void that houses the instrumentation system; an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve; and at least one thermoelectric cooler positioned in the annular space, whereby the at least one thermoelectric cooler prevents the instrumentation from attaining a predetermined temperature set-point.
 6. A modular cooling device for a cylindrical drilling instrumentation system, comprising: an inner sleeve; an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve; and at least one thermoelectric cooler positioned in the annular space, wherein the inner sleeve fits around and is in direct contact with the drilling instrumentation system.
 7. A method of cooling electrical components located in a downhole drill string comprising locating a downhole drill string in a drill hole, wherein the drill string comprises an inner sleeve, an outer sleeve concentric with the inner sleeve and aligned along a same axis as the inner sleeve, creating a first annular space between the inner sleeve and the outer sleeve, and at least one thermoelectric cooler (TEC) positioned in the annular space
 8. The method of claim 7, wherein the electrical components are located in and are in direct contact with the inner sleeve.
 9. The method of claim 7, wherein the at least one TEC is supplied with energy to cool the electrical components located in the inner sleeve during a drilling process.
 10. The method of claim 9, wherein the drilling process is a directional drilling process.
 11. The method of claim 7, wherein the annular space between the inner sleeve and the outer sleeve comprises an insulating material.
 12. The method of claim 11, wherein the insulating material is selected from an expandable epoxy and a gas. 